A GIS based Fuzzy-AHP for delineating groundwater potential zones in tropical river basin, southern part of India

Abstract

Groundwater plays a vital role in the development of ecological niches, the durability of the environment, and the socio-economic growth of an area. To meet the demand for groundwater over the increasing population, the scientific community stresses the prospective of identifying groundwater potential zones (GWPZ), aiming at conservation, planning, and regulation for optimum utilization of this natural resource. The GWPZ evaluation of the Karuvannur River Basin (KRB) in the southern part of India was carried out through GIS-Fuzzy-Analytical Hierarchy Process (FAHP), by assigning weights to interdependent factors controlling groundwater potentials such as geomorphology (Gm), slope(S), geology(G), drainage density (Dd), lineament density (Ld) and Land Use Land Cover (Lu) with the aid of Geographical Information system (GIS). FAHP includes a pairwise comparison of criteria and sub-criteria elements expressed with Triangular Fuzzy Numbers (TFNs), which can avoid vagueness, imprecision, and uncertainty of the linguistic scale. The model result was validated with the depth to water level data of dug wells by plotting them on the GWPZ map. This study reveals that the FAHP method is efficient in delineating GWPZ in this region with an accuracy of 80.9%. Further, GWPZ are reliant on underlying lithology; very good (48.1%) aquifers occupy the coastal area; good (12.7%); moderate (18.3%) aquifers are provided by the secondary porosity provided by underlying structures while poor aquifers (20.9%) occupy the eastern hard rock areas of KRB. This type of cost-effective FAHP method is efficient in delineating GWPZ and can be used for sustainable groundwater policies and management.